Liberals often fail to understand the fault lines that run through the Republican Party. But when those fault lines mirror their own, you would think they’d get it.

Even as President Obama rakes in $35,000 per couple at lavish fundraisers after relying on Goldman Sachs to be his largest single donor in 2008, the left sits in a park in Manhattan decrying Wall Street excesses. The Dodd-Frank bill, sold as a measure to crack down on Wall Street, is killing community and small banks throughout the nation, hastening the day when Wall Street will be the only source of corporate or personal lending.

Meanwhile, on the Republican side, voters have clearly opted for a candidate who came from the private sector rather than one who lived his life in politics, as the continuing collapse of Rick Perry and the ongoing ascendancy of Mitt Romney and Herman Cain attest. But which private sector? Wall street and big business, or small business? Between Romney and Cain, a new chasm is emerging. As Cain put it: “Mitt generated jobs on Wall Street. I did it on Main Street.”

The same discontent that is brewing over in Lower Manhattan among the extreme left is also raging on the right as small businessmen rally to Cain, emphatically making it clear that the needs of big business are not only not their needs, but often are a direct contradiction.

In a sense, the fault lines the Romney/Cain contest is exposing are very similar to those that first made their appearance when Arizona’s Barry Goldwater defeated New York’s Nelson Rockefeller for the Republican nomination for president in 1964. The split in the GOP has only grown wider. The evangelical, small-business, economic-freedom, anti-tax and anti-regulation Tea Party vote is lining up behind Cain. The economic-growth conservatives, corporate executives, free-market economists and GOP establishment are backing Romney.

The emerging contest will not be so much the right versus the center as it will be big versus small, the establishment versus insurgents, libertarian Republicans against social conservatives and, yes, Wall Street versus Main Street.

We are going to be treated to a presidential campaign in which both parties’ candidates will have to cope with increasing animosity toward the greed and self-serving refusal to be accountable that have characterized Wall Street and the financial industry.

But it is particularly intriguing to compare the impetus for the Cain candidacy with that of the Occupy Wall Street group. Both decry the tendency toward bigness and each disapproves of massive corporate bailouts that choose winners and losers. Both are opposed to crony capitalism and do not want the federal government to be a servant of the financial industry.

And both find themselves in opposition to the mainstream of their political parties. The world is indeed round, with apologies to Thomas Friedman. The far left and the far right unite in their opposition to big business and to the centrist establishments of both parties that maintain cozy and symbiotic relationships with Wall Street.

Can Obama continue to run on Wall Street money while backed by Occupy Wall Street foot soldiers? It seems unlikely. Can Cain tap into the resentment against Wall Street that rises from the demonstrators in Lower Manhattan? Perhaps he can.

The real criticism of Obama is not that he is a socialist — advocating government ownership and control of business. It is that he is a corporatist — advocating government control while keeping ownership in private hands. He wants a few big companies and a handful of major banks, the big labor unions and the federal government to work together to divide the pie and deal the cards. He wants to establish here a corporatism reminiscent of de Gaulle’s France and modern-day Germany. Soon the left will realize what the right is already coming to know — that the mainstream of each party is hopelessly in bed with Wall Street.